H-bridge

[adrianvon]

Hi,

I want to control a wiper motor (12v 2A) from a PIC18F microcontroller. Is the H-bridge in the attached pdf file good to use? and can i connect 'Q DRIVE' and 'INVERTED Q DRIVE' directly to the PIC ?

Thanks in advance.

 

[Reloadron]

The problem I potentially see is that the PIC may not be able to turn on the MOSFETs as the gate voltage applied would only be about 5 volts. This is where you will likely need to add something to get the gate voltage up. You may want to include some opto couplers in the scheme as gate drivers for the MOSFETs. So as drawn using 5 volts on the gates I don't think it will work well.

Ron

 

[adrianvon]

Hi,

Can i connect two bc526 with the inputs of the H-bridge and supply them to turn the H-bridge on ?

 

[Reloadron]

I did not look at the BC526 data sheet but yes, you could use any general purpose PNP switching transistor configured as a switch. I am just in the opto coupler habit with uC chips.

Maybe another forum member has some thoughts and will come along.

Ron

 

[Boncuk]

Hi adrianvon,

with a load of 2A the H-bridge should work fine.

If you want to go for maximum drain current (62A) you will have to use a gate driver circuit supplying at least ±10V gate voltage. (+ for the IRF3707 and - for the IRF4905)

I use the IRF3708 with the gate connected directly to an ATMEL CPU and it performs like a charm.

You won't need those bulky 1N5401s. Look out for the SB160. It has a DO-41 package and will handle EMF properly.


Boncuk

 

[Reloadron]

Thanks Hans, I just wasn't sure the gate would have adequate drive.

Ron

 

[adrianvon]

Hi,

Thanks for your replies. Are the diodes necessary, since these Mosfets have an internal diode?